Mayweather is world's highest paid athlete

Retired boxer Floyd Mayweather was the highest paid athlete in the world last year, according to Forbes' 2018 global list of the best paid athletes.

Floyd Mayweather is the world's highest paid athlete. (AAP)

Retired boxer Floyd Mayweather has reclaimed first place from football superstar Cristiano Ronaldo in Forbes' 2018 list of the world's 100 highest-paid athletes.

The 41-year-old American's earnings from last year's fight with Irishman Conor McGregor made him the world's best paid for the fourth time in seven years, with $US285 million.

Real Madrid striker Ronaldo ($US108 million) fell to third, behind soccer rival Lionel Messi ($US111 million).

Only the top three had earnings surpassing $US100 million.

Irish mixed martial artist McGregor ($US99 million) and Paris St Germain's Neymar ($US90 million) were fourth and fifth, respectively, but for the first time since 2010 there was not a single woman on the list.

Serena Williams, winner of 23 grand slam tennis singles titles, was the sole female representative last year but she has since largely been inactive owing to pregnancy and giving birth to her daughter Alexis in September.

Though still substantial, her $US18 million off-court earnings from sponsors were insufficient for her to make the top 100.

LeBron James (basketball), Roger Federer (tennis), Stephen Curry (basketball), Matt Ryan (American football) and Matthew Stafford (American football) concluded the top 10.

Barcelona's Argentine star Messi narrowly surpassed Ronaldo after signing a new contract at Barcelona, but the Portuguese, Mayweather and golfer Tiger Woods - this year ranked 16th - remained the only three to top the best-paid list during the past 18 years.

Fourth-placed McGregor's earnings represented almost double that of four-time Formula One world champion Lewis Hamilton ($US51 million).

Forbes' Top 10:

1 Floyd Mayweather, $US285 million

2 Lionel Messi, $US111 million

3 Cristiano Ronaldo, $US108 million

4 Conor McGregor, $US99 million

5 Neymar, $US90 million

6 LeBron James, $US85.5 million

7 Roger Federer, $US77.2million

8 Stephen Curry, $US76.9 million

9 Matt Ryan, $US67.3 million

10 Matthew Stanford, $US59.5 million

ALSO:

16 Tiger Woods, $US 43.3 million

45 Usain Bolt, $US31 million

83 Virat Kohli, $US24 million